Story: Soil investigation

Page 2 – Early investigations and bush sickness: 1900–1930

Experiments in soil surveying

As farming got under way, scientific expertise was needed
to direct the use of fertiliser, especially on less
productive land. Bernard Aston joined the Department of
Agriculture in 1900, and undertook systematic study of New
Zealand soils. He devised a standard set of tests for
identifying nutrients available in the soil, and undertook
nationwide soil fertility experiments.

The US Department of Agriculture set up a national soil
survey in 1899, and their first soil maps were published by
1911. Local surveys in New Zealand, largely experimental but
based on overseas experience, were made by Leonard Wild,
Hartley Ferrar and Bernard Aston. Ferrar, who had been
involved with soil surveys in Egypt, made detailed maps in
Northland and Central Otago using US methods of
classification. He and Aston were the first to adopt soil
types as a basic mapping unit – similar soil types were
grouped into series, and at the highest level into
provinces.

Wild about soils

In 1919, while teaching at Lincoln College, Leonard Wild
published Soils and manures of New Zealand. This
widely used textbook, found in many farmhouses, was
reprinted and updated several times over the next 40
years.

Influence of Theodore Rigg

Theodore Rigg, appointed agriculturalist at the Cawthron
Institute (Nelson) in 1920, brought academic experience from
the UK and US, and had a major influence on soil science in
New Zealand for the next 30 years. He introduced the hand
auger to extract soil samples. With J. A. Bruce he surveyed
Waimea county, producing one of the first detailed soil maps
in New Zealand.

Rigg attended the First International Soil Science
Congress in Washington DC in 1927, returning with new
insights into soil classification based on climate, geology,
texture and chemical composition. He believed that the whole
soil profile should be examined and recorded to the depth of
the parent rock, rather than just the organic-rich surface
layer. In his report on the congress, Rigg described the
Russian idea of soil zonality, which had a major influence on
New Zealand soil scientists in the 1930s and 1940s.

An organisational framework

Government science was reorganised in 1926. Ernest Marsden
became secretary to the Department of Scientific and
Industrial Research (DSIR), which merged the Geological
Survey and Dominion Laboratory. Recognising the importance of
agriculture to the New Zealand economy, Marsden set up a
small soil survey group within the Geological Survey. Rigg
was a member of the DSIR council from 1926 to 1954, and
promoted cooperation between the Cawthron Institute and DSIR
soil scientists.

Aston’s laboratory remained with the Department of
Agriculture, setting the scene for many years of
organisational rivalry.

Bush sickness

A wasting illness that affected sheep and cattle in the
central North Island was given the name bush sickness, and
was one of the most mystifying agricultural problems in the
first part of the 20th century. It was originally identified
as a form of iron deficiency by Aston in 1912, but it took
more than 20 years for the exact cause to be identified. This
was the catalyst for studies of the links between soils and
animal metabolism.

Competing for a cure

There was some rivalry in the search for a cure for bush
sickness. Elsa Kidson (Cawthron Institute) and K. J.
McNaught (Department of Agriculture) each developed
essentially the same methods for finding trace amounts of
cobalt. They published a series of papers on cobalt levels
in rocks, soils and pastures, while pointing out each
other’s errors.

Les Grange and Norman Taylor had studied volcanic ash
deposits (now called tephra) and had shown that bush sickness
only occurred where tephras had been deposited during the
Taupō and Kaharoa eruptions (about 200 AD and 1314 AD).
Chemical analyses revealed that the sickness was caused by a
deficiency in the trace element cobalt. Once identified it
was readily cured by adding tiny amounts of cobalt to
fertiliser. The success of the surveys and soil fertility
experiments meant that abandoned farms could become
productive.